Marcos, I made a new fresh instalation, just Worpress and Parent Theme of woffice (no Child theme yet), In Settings>General> Sites Language is set to Español.

I installed Loco Translation and as you can see in the Attachmet I selected "Spanish Spain" from Loco >Themes > Woffice, firt I made a Sync and then look for some words and phrases that have already been translated but they still appear in English

Thank you for the updates. Can you please provide us with your WordPress Dashboard access and FTP details? A further look is needed in order to determine what's going on. Thank you for your collaboration, have a nice day.

All the WordPress Dashboard and FTP access details should be sent in a private reply.

Thank you for the updates. I took a look into your website and it is properly using the translations files, I've made a test for the header welcome text (see attached images) and it is working properly. I changed the english setence using Loco Translate in your WordPress Dashboard and the theme properly used this translation. Please, let me know if you need any additional details. Have a nice day.

Thank you for the updates. Maybe you are missing some concepts here. Most theme strings are fully translatable with language files, however in some aspects WordPress will use whatever text your enter in your dashboard be it posts, pages, menus, widgets titles etc. In your case, the members page need to be edited in your Dashboard > Pages section, enter the prefered name and the page will use this name. Please, let me know if you need further details. Have a nice day.